text: /*
   * Copyright (c) 2017 Simon Goldschmidt
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice,
   *    this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
   * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
   * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
   * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
   * OF SUCH DAMAGE.
   *
   * This file is part of the lwIP TCP/IP stack.
   *
   * Author: Simon Goldschmidt <goldsimon@gmx.de>
   *
   */
  
  /* lwIP includes. */
  #include "lwip/debug.h"
  #include "lwip/def.h"
  #include "lwip/sys.h"
  #include "lwip/mem.h"
  #include "lwip/stats.h"
  #include "FreeRTOS.h"
  #include "semphr.h"
  #include "task.h"
  #include "lwip/arch.h"
  
  /** Set this to 1 if you want the stack size passed to sys_thread_new() to be
   * interpreted as number of stack words (FreeRTOS-like).
   * Default is that they are interpreted as byte count (lwIP-like).
   */
  #ifndef LWIP_FREERTOS_THREAD_STACKSIZE_IS_STACKWORDS
  #define LWIP_FREERTOS_THREAD_STACKSIZE_IS_STACKWORDS  0
  #endif
  
  /** Set this to 1 to use a mutex for SYS_ARCH_PROTECT() critical regions.
   * Default is 0 and locks interrupts/scheduler for SYS_ARCH_PROTECT().
   */
  #ifndef LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX
  #define LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX     0
  #endif
  
  /** Set this to 1 to include a sanity check that SYS_ARCH_PROTECT() and
   * SYS_ARCH_UNPROTECT() are called matching.
   */
  #ifndef LWIP_FREERTOS_SYS_ARCH_PROTECT_SANITY_CHECK
  #define LWIP_FREERTOS_SYS_ARCH_PROTECT_SANITY_CHECK   0
  #endif
  
  /** Set this to 1 to let sys_mbox_free check that queues are empty when freed */
  #ifndef LWIP_FREERTOS_CHECK_QUEUE_EMPTY_ON_FREE
  #define LWIP_FREERTOS_CHECK_QUEUE_EMPTY_ON_FREE       0
  #endif
  
  /** Set this to 1 to enable core locking check functions in this port.
   * For this to work, you'll have to define LWIP_ASSERT_CORE_LOCKED()
   * and LWIP_MARK_TCPIP_THREAD() correctly in your lwipopts.h! */
  #ifndef LWIP_FREERTOS_CHECK_CORE_LOCKING
  #define LWIP_FREERTOS_CHECK_CORE_LOCKING              0
  #endif
  
  /** Set this to 0 to implement sys_now() yourself, e.g. using a hw timer.
   * Default is 1, where FreeRTOS ticks are used to calculate back to ms.
   */
  #ifndef LWIP_FREERTOS_SYS_NOW_FROM_FREERTOS
  #define LWIP_FREERTOS_SYS_NOW_FROM_FREERTOS           1
  #endif
  
  /** Set this to 1 not to use recursive mutex
   * Default is 0.
   */
  #ifndef LWIP_FREERTOS_SYS_ARCH_NOT_USE_RECURSIVE_MUTEX
  #define LWIP_FREERTOS_SYS_ARCH_NOT_USE_RECURSIVE_MUTEX 0
  #endif
  
  /** Set this to 0 to show assert log in sys_mbox functions
   * For this to work, you'll have to increase downlink throughput
   * Default is 0
   */
  #ifndef LWIP_FREERTOS_SYS_ARCH_LOG
  #define LWIP_FREERTOS_SYS_ARCH_LOG           0
  #endif
  
  #if !LWIP_FREERTOS_SYS_ARCH_LOG
  #ifdef LWIP_ASSERT
  #undef LWIP_ASSERT
  #endif
  #define LWIP_ASSERT(message, assertion)
  #endif
  
  #if !configSUPPORT_DYNAMIC_ALLOCATION
  # error "lwIP FreeRTOS port requires configSUPPORT_DYNAMIC_ALLOCATION"
  #endif
  #if !INCLUDE_vTaskDelay
  # error "lwIP FreeRTOS port requires INCLUDE_vTaskDelay"
  #endif
  #if !INCLUDE_vTaskSuspend
  # error "lwIP FreeRTOS port requires INCLUDE_vTaskSuspend"
  #endif
  #if LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX || !LWIP_COMPAT_MUTEX
  #if !configUSE_MUTEXES
  # error "lwIP FreeRTOS port requires configUSE_MUTEXES"
  #endif
  #endif
  
  #if SYS_LIGHTWEIGHT_PROT && LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX
    #if LWIP_FREERTOS_SYS_ARCH_NOT_USE_RECURSIVE_MUTEX
    static sys_mutex_t g_lwip_mutex;
    #else
    static SemaphoreHandle_t sys_arch_protect_mutex;
    #endif
  #endif
  #if SYS_LIGHTWEIGHT_PROT && LWIP_FREERTOS_SYS_ARCH_PROTECT_SANITY_CHECK
  static sys_prot_t sys_arch_protect_nesting;
  #endif
  
  /* Initialize this module (see description in sys.h) */
  void
  sys_init(void)
  {
  #if SYS_LIGHTWEIGHT_PROT && LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX
    #if LWIP_FREERTOS_SYS_ARCH_NOT_USE_RECURSIVE_MUTEX
    sys_mutex_new(&g_lwip_mutex);
    #else
    /* initialize sys_arch_protect global mutex */
    sys_arch_protect_mutex = xSemaphoreCreateRecursiveMutex();
    LWIP_ASSERT("failed to create sys_arch_protect mutex",
      sys_arch_protect_mutex != NULL);
    #endif
  #endif /* SYS_LIGHTWEIGHT_PROT && LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX */
  }
  
  #if configUSE_16_BIT_TICKS == 1
  #error This port requires 32 bit ticks or timer overflow will fail
  #endif
  
  #if LWIP_FREERTOS_SYS_NOW_FROM_FREERTOS
  u32_t
  sys_now(void)
  {
    return xTaskGetTickCount() * portTICK_PERIOD_MS;
  }
  #endif
  
  u32_t
  sys_jiffies(void)
  {
    return xTaskGetTickCount();
  }
  
  #if SYS_LIGHTWEIGHT_PROT
  
  sys_prot_t
  sys_arch_protect(void)
  {
  #if LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX
    #if LWIP_FREERTOS_SYS_ARCH_NOT_USE_RECURSIVE_MUTEX
    sys_mutex_lock(&g_lwip_mutex);
    #else
    BaseType_t ret;
    LWIP_ASSERT("sys_arch_protect_mutex != NULL", sys_arch_protect_mutex != NULL);
  
    ret = xSemaphoreTakeRecursive(sys_arch_protect_mutex, portMAX_DELAY);
    LWIP_ASSERT("sys_arch_protect failed to take the mutex", ret == pdTRUE);
    #endif
  #else /* LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX */
    taskENTER_CRITICAL();
  #endif /* LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX */
  #if LWIP_FREERTOS_SYS_ARCH_PROTECT_SANITY_CHECK
    {
      /* every nested call to sys_arch_protect() returns an increased number */
      sys_prot_t ret = sys_arch_protect_nesting;
      sys_arch_protect_nesting++;
      LWIP_ASSERT("sys_arch_protect overflow", sys_arch_protect_nesting > ret);
      return ret;
    }
  #else
    return 1;
  #endif
  }
  
  void
  sys_arch_unprotect(sys_prot_t pval)
  {
  #if LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX
    BaseType_t ret;
  #endif
  #if LWIP_FREERTOS_SYS_ARCH_PROTECT_SANITY_CHECK
    LWIP_ASSERT("unexpected sys_arch_protect_nesting", sys_arch_protect_nesting > 0);
    sys_arch_protect_nesting--;
    LWIP_ASSERT("unexpected sys_arch_protect_nesting", sys_arch_protect_nesting == pval);
  #endif
  
  #if LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX
    #if LWIP_FREERTOS_SYS_ARCH_NOT_USE_RECURSIVE_MUTEX
    sys_mutex_unlock(&g_lwip_mutex);
    #else
    LWIP_ASSERT("sys_arch_protect_mutex != NULL", sys_arch_protect_mutex != NULL);
  
    ret = xSemaphoreGiveRecursive(sys_arch_protect_mutex);
    LWIP_ASSERT("sys_arch_unprotect failed to give the mutex", ret == pdTRUE);
    #endif
  #else /* LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX */
    taskEXIT_CRITICAL();
  #endif /* LWIP_FREERTOS_SYS_ARCH_PROTECT_USES_MUTEX */
    LWIP_UNUSED_ARG(pval);
  }
  
  #endif /* SYS_LIGHTWEIGHT_PROT */
  
  void
  sys_arch_msleep(u32_t delay_ms)
  {
    TickType_t delay_ticks = delay_ms / portTICK_RATE_MS;
    vTaskDelay(delay_ticks);
  }
  
  #if !LWIP_COMPAT_MUTEX
  
  /* Create a new mutex*/
  err_t
  sys_mutex_new(sys_mutex_t *mutex)
  {
    LWIP_ASSERT("mutex != NULL", mutex != NULL);
  
    mutex->mut = xSemaphoreCreateRecursiveMutex();
    if(mutex->mut == NULL) {
      SYS_STATS_INC(mutex.err);
      return ERR_MEM;
    }
    SYS_STATS_INC_USED(mutex);
    return ERR_OK;
  }
  
  void
  sys_mutex_lock(sys_mutex_t *mutex)
  {
    #if LWIP_FREERTOS_SYS_ARCH_NOT_USE_RECURSIVE_MUTEX
    while( xSemaphoreTake( mutex->mut, portMAX_DELAY ) != pdTRUE );
    #else
    BaseType_t ret;
    LWIP_ASSERT("mutex != NULL", mutex != NULL);
    LWIP_ASSERT("mutex->mut != NULL", mutex->mut != NULL);
  
    ret = xSemaphoreTakeRecursive(mutex->mut, portMAX_DELAY);
    LWIP_ASSERT("failed to take the mutex", ret == pdTRUE);
    #endif
  }
  
  void
  sys_mutex_unlock(sys_mutex_t *mutex)
  {
    #if LWIP_FREERTOS_SYS_ARCH_NOT_USE_RECURSIVE_MUTEX
    xSemaphoreGive( mutex->mut );
    #else
    BaseType_t ret;
    LWIP_ASSERT("mutex != NULL", mutex != NULL);
    LWIP_ASSERT("mutex->mut != NULL", mutex->mut != NULL);
  
    ret = xSemaphoreGiveRecursive(mutex->mut);
    LWIP_ASSERT("failed to give the mutex", ret == pdTRUE);
    #endif
  }
  
  void
  sys_mutex_free(sys_mutex_t *mutex)
  {
    LWIP_ASSERT("mutex != NULL", mutex != NULL);
    LWIP_ASSERT("mutex->mut != NULL", mutex->mut != NULL);
  
    SYS_STATS_DEC(mutex.used);
    vSemaphoreDelete(mutex->mut);
    mutex->mut = NULL;
  }
  
  #endif /* !LWIP_COMPAT_MUTEX */
  
  err_t
  sys_sem_new(sys_sem_t *sem, u8_t initial_count)
  {
    LWIP_ASSERT("sem != NULL", sem != NULL);
    LWIP_ASSERT("initial_count invalid (not 0 or 1)",
      (initial_count == 0) || (initial_count == 1));
  
    sem->sem = xSemaphoreCreateBinary();
    if(sem->sem == NULL) {
      SYS_STATS_INC(sem.err);
      return ERR_MEM;
    }
    SYS_STATS_INC_USED(sem);
  
    if(initial_count == 1) {
      BaseType_t ret = xSemaphoreGive(sem->sem);
      LWIP_ASSERT("sys_sem_new: initial give failed", ret == pdTRUE);
    }
    return ERR_OK;
  }
  
  void
  sys_sem_signal(sys_sem_t *sem)
  {
    BaseType_t ret;
    LWIP_ASSERT("sem != NULL", sem != NULL);
    LWIP_ASSERT("sem->sem != NULL", sem->sem != NULL);
  
    ret = xSemaphoreGive(sem->sem);
    /* queue full is OK, this is a signal only... */
    LWIP_ASSERT("sys_sem_signal: sane return value",
      (ret == pdTRUE) || (ret == errQUEUE_FULL));
  }
  
  u32_t
  sys_arch_sem_wait(sys_sem_t *sem, u32_t timeout_ms)
  {
    BaseType_t ret;
    LWIP_ASSERT("sem != NULL", sem != NULL);
    LWIP_ASSERT("sem->sem != NULL", sem->sem != NULL);
  
    if(!timeout_ms) {
      /* wait infinite */
      ret = xSemaphoreTake(sem->sem, portMAX_DELAY);
      LWIP_ASSERT("taking semaphore failed", ret == pdTRUE);
    } else {
      TickType_t timeout_ticks = timeout_ms / portTICK_RATE_MS;
      ret = xSemaphoreTake(sem->sem, timeout_ticks);
      if (ret == errQUEUE_EMPTY) {
        /* timed out */
        return SYS_ARCH_TIMEOUT;
      }
      LWIP_ASSERT("taking semaphore failed", ret == pdTRUE);
    }
  
    /* Old versions of lwIP required us to return the time waited.
       This is not the case any more. Just returning != SYS_ARCH_TIMEOUT
       here is enough. */
    return 1;
  }
  
  void
  sys_sem_free(sys_sem_t *sem)
  {
    LWIP_ASSERT("sem != NULL", sem != NULL);
    LWIP_ASSERT("sem->sem != NULL", sem->sem != NULL);
  
    SYS_STATS_DEC(sem.used);
    vSemaphoreDelete(sem->sem);
    sem->sem = NULL;
  }
  
  err_t
  sys_mbox_new(sys_mbox_t *mbox, int size)
  {
    LWIP_ASSERT("mbox != NULL", mbox != NULL);
    LWIP_ASSERT("size > 0", size > 0);
  
    mbox->mbx = xQueueCreate((UBaseType_t)size, sizeof(void *));
    if(mbox->mbx == NULL) {
      SYS_STATS_INC(mbox.err);
      return ERR_MEM;
    }
    SYS_STATS_INC_USED(mbox);
    return ERR_OK;
  }
  
  void
  sys_mbox_post(sys_mbox_t *mbox, void *msg)
  {
    BaseType_t ret;
    LWIP_ASSERT("mbox != NULL", mbox != NULL);
    LWIP_ASSERT("mbox->mbx != NULL", mbox->mbx != NULL);
  
    ret = xQueueSendToBack(mbox->mbx, &msg, portMAX_DELAY);
    LWIP_ASSERT("mbox post failed", ret == pdTRUE);
  }
  
  err_t
  sys_mbox_trypost(sys_mbox_t *mbox, void *msg)
  {
    BaseType_t ret;
    LWIP_ASSERT("mbox != NULL", mbox != NULL);
    LWIP_ASSERT("mbox->mbx != NULL", mbox->mbx != NULL);
  
    ret = xQueueSendToBack(mbox->mbx, &msg, 0);
    if (ret == pdTRUE) {
      return ERR_OK;
    } else {
      LWIP_ASSERT("mbox trypost failed", ret == errQUEUE_FULL);
      SYS_STATS_INC(mbox.err);
      return ERR_MEM;
    }
  }
  
  err_t
  sys_mbox_trypost_fromisr(sys_mbox_t *mbox, void *msg)
  {
    BaseType_t ret;
    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
    LWIP_ASSERT("mbox != NULL", mbox != NULL);
    LWIP_ASSERT("mbox->mbx != NULL", mbox->mbx != NULL);
  
    ret = xQueueSendToBackFromISR(mbox->mbx, &msg, &xHigherPriorityTaskWoken);
    if (ret == pdTRUE) {
      if (xHigherPriorityTaskWoken == pdTRUE) {
        return ERR_NEED_SCHED;
      }
      return ERR_OK;
    } else {
      LWIP_ASSERT("mbox trypost failed", ret == errQUEUE_FULL);
      SYS_STATS_INC(mbox.err);
      return ERR_MEM;
    }
  }
  
  u32_t
  sys_arch_mbox_fetch(sys_mbox_t *mbox, void **msg, u32_t timeout_ms)
  {
    BaseType_t ret;
    void *msg_dummy;
    LWIP_ASSERT("mbox != NULL", mbox != NULL);
    LWIP_ASSERT("mbox->mbx != NULL", mbox->mbx != NULL);
  
    if (!msg) {
      msg = &msg_dummy;
    }
  
    if (!timeout_ms) {
      /* wait infinite */
      ret = xQueueReceive(mbox->mbx, &(*msg), portMAX_DELAY);
      LWIP_ASSERT("mbox fetch failed", ret == pdTRUE);
    } else {
      TickType_t timeout_ticks = timeout_ms / portTICK_RATE_MS;
      ret = xQueueReceive(mbox->mbx, &(*msg), timeout_ticks);
      if (ret == errQUEUE_EMPTY) {
        /* timed out */
        *msg = NULL;
        return SYS_ARCH_TIMEOUT;
      }
      LWIP_ASSERT("mbox fetch failed", ret == pdTRUE);
    }
  
    /* Old versions of lwIP required us to return the time waited.
       This is not the case any more. Just returning != SYS_ARCH_TIMEOUT
       here is enough. */
    return 1;
  }
  
  u32_t
  sys_arch_mbox_tryfetch(sys_mbox_t *mbox, void **msg)
  {
    BaseType_t ret;
    void *msg_dummy;
    LWIP_ASSERT("mbox != NULL", mbox != NULL);
    LWIP_ASSERT("mbox->mbx != NULL", mbox->mbx != NULL);
  
    if (!msg) {
      msg = &msg_dummy;
    }
  
    ret = xQueueReceive(mbox->mbx, &(*msg), 0);
    if (ret == errQUEUE_EMPTY) {
      *msg = NULL;
      return SYS_MBOX_EMPTY;
    }
    LWIP_ASSERT("mbox fetch failed", ret == pdTRUE);
  
    /* Old versions of lwIP required us to return the time waited.
       This is not the case any more. Just returning != SYS_ARCH_TIMEOUT
       here is enough. */
    return 1;
  }
  
  void
  sys_mbox_free(sys_mbox_t *mbox)
  {
    LWIP_ASSERT("mbox != NULL", mbox != NULL);
    LWIP_ASSERT("mbox->mbx != NULL", mbox->mbx != NULL);
  
  #if LWIP_FREERTOS_CHECK_QUEUE_EMPTY_ON_FREE
    {
      UBaseType_t msgs_waiting = uxQueueMessagesWaiting(mbox->mbx);
      LWIP_ASSERT("mbox quence not empty", msgs_waiting == 0);
  
      if (msgs_waiting != 0) {
        SYS_STATS_INC(mbox.err);
      }
    }
  #endif
  
    vQueueDelete(mbox->mbx);
  
    SYS_STATS_DEC(mbox.used);
  }
  
  sys_thread_t
  sys_thread_new(const char *name, lwip_thread_fn thread, void *arg, int stacksize, int prio)
  {
    TaskHandle_t rtos_task;
    BaseType_t ret;
    sys_thread_t lwip_thread;
    size_t rtos_stacksize;
  
    LWIP_ASSERT("invalid stacksize", stacksize > 0);
  #if LWIP_FREERTOS_THREAD_STACKSIZE_IS_STACKWORDS
    rtos_stacksize = (size_t)stacksize;
  #else
    rtos_stacksize = (size_t)stacksize / sizeof(StackType_t);
  #endif
  
    /* lwIP's lwip_thread_fn matches FreeRTOS' TaskFunction_t, so we can pass the
       thread function without adaption here. */
    ret = xTaskCreate(thread, name, (configSTACK_DEPTH_TYPE)rtos_stacksize, arg, prio, &rtos_task);
    LWIP_ASSERT("task creation failed", ret == pdTRUE);
  
    lwip_thread.thread_handle = rtos_task;
    return lwip_thread;
  }
  
  #if LWIP_NETCONN_SEM_PER_THREAD
  #if configNUM_THREAD_LOCAL_STORAGE_POINTERS > 0
  
  sys_sem_t *
  sys_arch_netconn_sem_get(void)
  {
    void* ret;
    TaskHandle_t task = xTaskGetCurrentTaskHandle();
    LWIP_ASSERT("task != NULL", task != NULL);
  
    ret = pvTaskGetThreadLocalStoragePointer(task, 0);
    return ret;
  }
  
  void
  sys_arch_netconn_sem_alloc(void)
  {
    void *ret;
    TaskHandle_t task = xTaskGetCurrentTaskHandle();
    LWIP_ASSERT("task != NULL", task != NULL);
  
    ret = pvTaskGetThreadLocalStoragePointer(task, 0);
    if(ret == NULL) {
      sys_sem_t *sem;
      err_t err;
      /* need to allocate the memory for this semaphore */
      sem = mem_malloc(sizeof(sys_sem_t));
      LWIP_ASSERT("sem != NULL", sem != NULL);
      err = sys_sem_new(sem, 0);
      LWIP_ASSERT("err == ERR_OK", err == ERR_OK);
      LWIP_ASSERT("sem invalid", sys_sem_valid(sem));
      vTaskSetThreadLocalStoragePointer(task, 0, sem);
    }
  }
  
  void sys_arch_netconn_sem_free(void)
  {
    void* ret;
    TaskHandle_t task = xTaskGetCurrentTaskHandle();
    LWIP_ASSERT("task != NULL", task != NULL);
  
    ret = pvTaskGetThreadLocalStoragePointer(task, 0);
    if(ret != NULL) {
      sys_sem_t *sem = ret;
      sys_sem_free(sem);
      mem_free(sem);
      vTaskSetThreadLocalStoragePointer(task, 0, NULL);
    }
  }
  
  #else /* configNUM_THREAD_LOCAL_STORAGE_POINTERS > 0 */
  #error LWIP_NETCONN_SEM_PER_THREAD needs configNUM_THREAD_LOCAL_STORAGE_POINTERS
  #endif /* configNUM_THREAD_LOCAL_STORAGE_POINTERS > 0 */
  
  #endif /* LWIP_NETCONN_SEM_PER_THREAD */
  
  #if LWIP_FREERTOS_CHECK_CORE_LOCKING
  #if LWIP_TCPIP_CORE_LOCKING
  
  /** Flag the core lock held. A counter for recursive locks. */
  static u8_t lwip_core_lock_count;
  static TaskHandle_t lwip_core_lock_holder_thread;
  extern sys_mutex_t lock_tcpip_core;
  
  void
  sys_lock_tcpip_core(void)
  {
     sys_mutex_lock(&lock_tcpip_core);
     if (lwip_core_lock_count == 0) {
       lwip_core_lock_holder_thread = xTaskGetCurrentTaskHandle();
     }
     lwip_core_lock_count++;
  }
  
  void
  sys_unlock_tcpip_core(void)
  {
     lwip_core_lock_count--;
     if (lwip_core_lock_count == 0) {
         lwip_core_lock_holder_thread = 0;
     }
     sys_mutex_unlock(&lock_tcpip_core);
  }
  
  #endif /* LWIP_TCPIP_CORE_LOCKING */
  
  #if !NO_SYS
  static TaskHandle_t lwip_tcpip_thread;
  #endif
  
  void
  sys_mark_tcpip_thread(void)
  {
  #if !NO_SYS
    lwip_tcpip_thread = xTaskGetCurrentTaskHandle();
  #endif
  }
  
  void
  sys_check_core_locking(void)
  {
    /* Embedded systems should check we are NOT in an interrupt context here */
    /* E.g. core Cortex-M3/M4 ports:
           configASSERT( ( portNVIC_INT_CTRL_REG & portVECTACTIVE_MASK ) == 0 );
  
       Instead, we use more generic FreeRTOS functions here, which should fail from ISR: */
    taskENTER_CRITICAL();
    taskEXIT_CRITICAL();
  
  #if !NO_SYS
    if (lwip_tcpip_thread != 0) {
      TaskHandle_t current_thread = xTaskGetCurrentTaskHandle();
  
  #if LWIP_TCPIP_CORE_LOCKING
      LWIP_ASSERT("Function called without core lock",
                  current_thread == lwip_core_lock_holder_thread && lwip_core_lock_count > 0);
  #else /* LWIP_TCPIP_CORE_LOCKING */
      LWIP_ASSERT("Function called from wrong thread", current_thread == lwip_tcpip_thread);
  #endif /* LWIP_TCPIP_CORE_LOCKING */
    }
  #endif /* !NO_SYS */
  }
  
  #endif /* LWIP_FREERTOS_CHECK_CORE_LOCKING*/
  